Scanning method and apparatus in wireless access system

ABSTRACT

A method for scanning assigned carriers in a multicarrier system may include receiving a multicarrier advertisement message from a base station, the multicarrier advertisement message including scan reporting trigger control information of assigned secondary carriers, performing scanning for the assigned secondary carriers, and reporting the scan results to the base station when a specific metric measured by the scanning meets a condition set in the scan reporting trigger control information.

TECHNICAL FIELD

The present invention relates to a scanning method and apparatus, andmore particularly, a scanning method and apparatus for assignedsecondary carriers belonging to a base station.

BACKGROUND ART

Hereinafter, description will be briefly given of carriers.

A user may perform modulation on the amplitude, frequency, and/or phaseof a sine wave or a periodic pulse wave to include information which isdesired to be transmitted. Here, the sine wave or pulse wave serving toconvey information is called a carrier.

Methods for modulating a carrier include a single-carrier modulation(SCM) scheme and a multi-carrier modulation (MCM) scheme. The SCM schemeperforms modulation such that all information is carried on a singlecarrier.

The MCM scheme divides an entire bandwidth channel of one carrier intosubchannels having multiple narrow bandwidths and transmits multiplenarrowband subcarriers through respective subchannels.

When using the MCM scheme, each subchannel may approximate to a flatchannel due to a narrow bandwidth. A user may compensate for distortionof a channel using a simple equalizer. The MCM scheme may be implementedat a high speed using Fast Fourier Transform (FFT). Namely, the MCMscheme is favorable during high-rate data transmission as compared tothe SCM scheme.

As the capabilities of a base station and/or a terminal have beendeveloped, a frequency bandwidth which can be provided or used by thebase station and/or the terminal has been enlarged. Accordingly, in theembodiments of the present invention, a multi-carrier system supportingbroadband by aggregating one or more carriers is proposed.

Specifically, the multi-carrier system, which will be describedhereafter, uses carriers by aggregating one or more carriers, unlike theafore-mentioned MCM scheme which uses carriers by segregating onecarrier.

To efficiently use multiple bands or multiple carriers, a technique inwhich one medium access control (MAC) entity manages multiple carriers(e.g., multiple frequency carriers (FCs)) has been proposed.

FIGS. 1( a) and 1 (b) illustrate methods for transmitting and receivingsignals based on a multi-band radio frequency (RF) scheme.

In FIG. 1, one MAC layer in each of a transmitting end and a receivingend may manage multiple carriers to efficiently use the multiplecarriers. To effectively transmit and receive the multiple carriers, itis assumed that both the transmitting end and the receiving end cantransmit and receive the multiple carriers. Since frequency carriersmanaged by one MAC layer do not need to be contiguous, the above methodenables flexible resource management. More specifically, the frequencycarriers may have contiguous aggregation or non-contiguous aggregation.

In FIGS. 1( a) and 1 (b), physical layers (PHY 0, PHY 1, . . . , PHYn-2, and PHYn-1) represent multiple bands and each of the bands may havea frequency carrier (FC) size allocated for a specific service accordingto a predetermined frequency policy. For example, PHY 0 (RF carrier 0)may have a frequency band size allocated for a general FM radiobroadcast and PHY 1 (RF carrier 1) may have a frequency band sizeallocated for cellular phone communication.

Although each frequency band may have a different FA size depending onthe characteristics thereof, it is assumed in the following descriptionthat each frequency carrier (FC) has a size of A MHz for convenience ofexplanation. Each frequency allocation (FA) band may be represented by acarrier frequency that enables a baseband signal to be used in eachfrequency band. Thus, in the following description, each FA will bereferred to as a “carrier frequency band” or will simply be referred toas a “carrier” representing each carrier frequency band unless such usecauses confusion.

As in the recent 3 rd generation partnership project (3GPP) long termevolution-advanced (LTE-A), the carrier may also be referred to as a“component carrier” to discriminate it from a subcarrier used in themulti-carrier system.

As such, the “multi-band” scheme may also be referred to as a“multi-carrier” scheme or a “carrier aggregation” scheme.

FIG. 2 is a view illustrating an example of the use of multiple carriersin a general wireless communication system.

The multiple carriers of general technology may employ contiguouscarrier aggregation as shown in FIG. 2( a) or non-contiguous carrieraggregation as shown in FIG. 2( b). The combination unit of suchcarriers is a basic bandwidth unit of a general legacy system (e.g.,Long Term Evolution (LTE) in an LTE-advanced system or IEEE 802.16e inan IEEE 802.16m system).

In a multi-carrier environment of general technology, two types ofcarriers are defined as follows.

First, a first carrier (also called a primary carrier) is the carrierused by a Base Station (BS) and a Mobile Station (MS) to exchangetraffic and full PHY/MAC control information. Further, the primarycarrier is used for control functions for proper MS operation, such asnetwork entry. Each MS shall have only one primary carrier per cell.

A second carrier (also called a secondary carrier) is an additionalcarrier which the terminal may use for traffic exchange, only per basestation's specific allocation commands and rules, typically received onthe primary carrier. The secondary carrier may also include controlsignaling to support multi-carrier operations.

In the general technology, the carriers of a multi-carrier system basedon the above-described primary and secondary carriers may be classifiedinto a fully configured carrier and a partially configured carrier.

First, the fully configured carrier is a carrier for which all controlsignaling actions are configured. Further, information and parametersregarding multi-carrier operations and the other carriers can also beincluded in the control channels.

The partially configured carrier is a carrier in which all controlchannels for supporting downlink (DL) transmission in a downlink carrierother than an uplink carrier, present as a pair with the downlinkcarrier, during Time Division Duplexing (TDD) DL transmission or inFrequency Division Duplexing (FDD) mode are configured.

Generally, a terminal may perform initial network entry through aprimary carrier, and may exchange mutual multi-carrier capabilityinformation in a registration process for exchanging an Advanced AirInterface (AAI) registration request response (AAI_REG-REQ/RSP) messagewith a base station.

DISCLOSURE OF THE INVENTION

Therefore, an aspect of this specification is to provide a method forobviating a terminal from performing unnecessary scanning operations forthe same assigned carrier by transmitting an indicator indicatingwhether or not to scan the assigned carriers to the terminal, in amulticarrier system.

Another aspect of this specification is to provide definition of atrigger condition for carrier management (as one example, secondarycarrier activation/primary carrier change), and a method fortransmitting the defined trigger conditions.

Another aspect of this specification is to provide a method forobviating failure of instruction given by a base station to activate aspecific secondary carrier, by performing scanning for inactive assignedsecondary carriers and transmitting the scan results to the basestation.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described herein,there is provided a method for scanning assigned carriers in amulticarrier system including receiving a multicarrier advertisementmessage from a base station, the multicarrier advertisement messageincluding scan reporting trigger control information of assignedsecondary carriers, performing scanning for the assigned secondarycarriers, and reporting the scan results to the base station when aspecific metric measured by the scanning meets a condition set in thescan reporting trigger control information.

The scan results may be transmitted to the base station via a scanreporting (SCN-REP) message.

The specific metric may be a carrier to interference and noise ratio(CINR) or a received signal strength indicator (RSSI).

The assigned secondary carrier may be an inactive or active assignedsecondary carrier.

The scan results may be reported to the base station when a metricmeasured by scanning the inactive assigned secondary carrier is greaterthan a threshold value or a metric measured by scanning the activeassigned secondary carrier is less than a threshold value.

The scan reporting trigger control information may be a carrieractivation (CA) specific trigger field indicating a trigger conditionfor reporting the scan results of inactive secondary carriers among theassigned secondary carriers to the base station.

The method may further include receiving a scan response (SCN-RSP)message from the base station, the scan response message instructingscanning for the assigned secondary carriers.

The scan response message may be transmitted from the base station whendecided to activate an inactive secondary carrier is decided.

The method may further include receiving a carrier management command(CM-CMD) message from the base station, the carrier management commandmessage instructing activation and/or deactivation of the secondarycarriers.

The method may further include receiving a first message from the basestation, the first message including a scanning required indicatorindicating whether or not to scan the assigned secondary carriers.

The scanning required indicator may be 1-bit in size.

The first message may be one of a multicarrier response (MC-RSP)message, a multicarrier advertisement (MC-ADV) message, or a neighboradvertisement (NBR-ADV) message.

Whether or not to scan may be decided based upon coverage of theassigned secondary carrier.

In accordance with an exemplary embodiment, there is provided a terminalfor scanning assigned carriers in a multicarrier system, the terminalincluding a radio frequency unit configured to transmit and receiveradio signals to and from an exterior, and a controller configured tocontrol the radio frequency unit to receive a multicarrier advertisementmessage from a base station, the multicarrier advertisement messageincluding scan reporting trigger control information of assignedsecondary carriers, to perform scanning for the assigned secondarycarriers, and to control the radio frequency unit to report the scanresults to the base station when a specific metric measured by thescanning meets a condition set in the scan reporting trigger controlinformation.

The controller may control the radio frequency unit to report the scanresults to the base station when a metric measured by scanning theinactive assigned secondary carrier is greater than a threshold value ora metric measured by scanning the active assigned secondary carrier isless than a threshold value.

The controller may control the radio frequency unit to receive a scanresponse (SCN-RSP) message instructing scanning for an assignedsecondary carrier from the base station.

Effect of the Invention

This specification has an effect that a terminal may not performunnecessary scanning for assigned carriers, which have the samecoverage, by transmitting an indicator indicating whether or not to scanassigned carriers to the terminal in a multicarrier system.

This specification also has an effect of obviating failure ofinstruction given by a base station to activate a specific secondarycarrier by performing scanning for inactive assigned secondary carriersand transmitting the scan results to the base station.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 (a) and (b) illustrate a method for transmitting and receiving asignal based on a multi-band radio frequency (RF) scheme;

FIG. 2 is a view illustrating an example of the use of multiple carriersin a general wireless communication system;

FIG. 3 is a view illustrating an exemplary procedure for allowing a basestation to allocate (assign) one or more carriers to a terminal via acarrier management message (AAI_CM-CMD) in a broadband wireless accesssystem;

FIG. 4( a) illustrates that multiple carriers belonging to an arbitrarybase station have the same coverage, and FIG. 4( b) illustrates thatmultiple carriers belonging to an arbitrary base station have differentcoverage from each other;

FIG. 5 is flowchart illustrating a scanning method using a scanningrequired indicator in accordance with a first exemplary embodiment;

FIG. 6 is a flowchart illustrating a scanning method using a scanningrequired indicator and a carrier activation (CA) specific triggercondition in accordance with another exemplary embodiment;

FIG. 7 illustrates trigger values for scanning and scan reporting when aterminal moves toward a center of a cell according to a triggercondition 1 of the second exemplary embodiment;

FIG. 8 illustrates trigger values for scanning and scan reporting when aterminal moves away from a center of a cell according to a triggercondition 2 of the second exemplary embodiment;

FIG. 9 is a flowchart illustrating a method for reporting scan resultsof assigned secondary carriers according to a multicarrier (MC)-specifictrigger conditions in accordance with a third exemplary embodiment; and

FIG. 10 is a block diagram of a wireless communication system inaccordance with one exemplary embodiment.

MODES FOR CARRYING OUT THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments ofthis specification, examples of which are illustrated in theaccompanying drawings. It should be understood that the descriptionherein will be given of essential parts required to understandoperations according to this specification and description of the otherparts will be omitted to obviate obscurity of the point of theinvention.

Exemplary embodiments described hereinbelow are combinations of elementsand features of the present invention. The elements or features may beconsidered selective unless otherwise mentioned. Each element or featuremay be practiced without being combined with other elements or features.Further, an embodiment of the present invention may be constructed bycombining parts of the elements and/or features. Operation ordersdescribed in embodiments of the present invention may be rearranged.Some constructions or features of any one embodiment may be included inanother embodiment and may be replaced with corresponding constructionsof another embodiment.

In exemplary embodiments of the present invention, description is madeof a data transmission and reception relationship between a base station(BS) and a Mobile Station (MS). Herein, the term ‘BS’ refers to aterminal node of a network, which communicates directly with the MS. Insome cases, a specific operation described as performed by the BS may beperformed by an upper node of the BS.

Namely, it is apparent that, in a network comprised of a plurality ofnetwork nodes including a BS, various operations performed forcommunication with an MS may be performed by the BS, or network nodesother than the BS. The term ‘BS’ may be replaced with the term ‘fixedstation’, ‘Node B’, ‘eNode B (eNB)’, ‘access point’, ‘advanced basestation (ABS),’ etc. The term ‘MS’ may be replaced with the term ‘UserEquipment (UE)’, ‘Subscriber Station (SS’), ‘Mobile Subscriber Station(MSS)’, ‘mobile terminal’, ‘advanced mobile station (AMS),’ etc.

Exemplary embodiments of the present invention may be achieved byvarious means, for example, hardware, firmware, software, or acombination thereof.

In a hardware configuration, the methods according to exemplaryembodiments of the present invention may be achieved by one or moreApplication Specific Integrated Circuits (ASICs), Digital SignalProcessors (DSPs), Digital Signal Processing Devices (DSPDs),Programmable Logic Devices (PLDs), Field Programmable Gate Arrays(FPGAs), processors, controllers, microcontrollers, microprocessors,etc.

In a firmware or software configuration, the methods according to theexemplary embodiments of the present invention may be implemented in theform of a module, a procedure, a function, etc. performing theabove-described functions or operations. Software code may be stored ina memory unit and executed by a processor. The memory unit is located atthe interior or exterior of the processor and may transmit and receivedata to and from the processor via various known means.

Specific terms used for the exemplary embodiments of the presentinvention are provided to help in understanding of the presentinvention. These specific terms may be replaced with other terms withinthe scope and spirit of the present invention.

Multicarrier Operation Mode

1. Multicarrier Aggregation

Multicarrier aggregation is a multicarrier mode in which a physicallayer connection of an AMS is maintained while the AMS executes datatransmission via a secondary carrier, and control signaling is monitoredvia a primary carrier.

2. Multicarrier Switching

Multicarrier switching is a multicarrier mode in which a physical layerconnection of an AMS is switched from a primary carrier to a fullyconfigured or partially configured secondary carrier by a base station(ABS)'s instruction to receive E-MBS service via the secondary carrier.

3. Basic MC Mode

Basic Multicarrier (MC) mode is a mode in which a terminal operates withonly a single carrier although it supports a primary carrier switchingprocedure as well as an optimized scanning of carriers related to amulticarrier operation.

Hereinafter, terms to be used in the multicarrier operation will bedefined.

1. Available Carrier: The available carrier refers to all carriersbelonging to the base station (ABS). The terminal may acquireinformation of the available carrier through an advanced air interfaceglobal carrier configuration (AAI_Global-config) message or amulticarrier advertisement (AAI_MC-ADV) message.

2. Assigned Carrier: The assigned carrier refers to a subset of anavailable carrier that is assigned to the AMS by the ABS. That is, theABS may assign at least one of its own available carriers as an assignedsecondary carrier of the AMS in consideration of the AMS capability.

3. Active Carrier: The active carrier refers to a carrier that is readyto perform data exchange between the AMS and the ABS, and may be asubset of the assigned carrier. Activation/deactivation of the assignedsecondary carrier may be dependent upon the decision of the ABS based ona Quality of Service (QoS) request. The ABS may inform the AMS ofinformation of whether to activate or deactivate a specific secondarycarrier through a carrier management command (AAI_CM-CMD) message.

Hereinafter, based on the above mentioned description, a procedure forallowing the base station to assign a carrier to the terminal withreference to FIG. 3.

FIG. 3 is a view illustrating an exemplary procedure for allowing a basestation (advanced base station; ABS) to assign at least one carrier to aterminal (advanced mobile station; AMS) via a carrier management command(AAI_CM-CMD) message in a broadband wireless access system.

As illustrated in FIG. 3, the AMS may perform an initial network entryincluding processes, such as scanning, ranging and the like, with theABS (S301).

The AMS and the ABS may exchange information related to multicarriercapabilities with each other via registration request/response(AAI_REG-REQ/RSP) messages (S302 and S303).

The ABS may transmit the AAI_REG-RSP message and transmit a globalcarrier configuration (AAI_Global-config) message (S304). TheAAI_Global-config message may include information related to all theavailable carriers supported in a network.

Also, the AMS may acquire information related to multicarrierconfiguration of the ABS by receiving a multicarrier advertisement(AAI_MC-ADV) message, which is periodically broadcast from the ABS(S305).

Afterwards, the AMS may inform the ABS of information about the AMS'ssupportable carriers through a multicarrier request (AAI_MC-REQ) messageaccording to multicarrier configurations of the ABS's available carriersusing the acquired information, such that it can request the list ofassigned carriers from the ABS.

The ABS may then decide a subset, which will be assigned as the AMS'ssecondary carrier, from among the ABS's available carriers on the basisof information received from the AMS, decide the list of assignedcarriers, and inform the AMS of the decided list of assigned carriersthrough a multicarrier response (AAI_MC-RSP) message (S307).

Thereafter, the ABS may transmit a carrier management command(AAI_CM-CMD) message to the AMS according to the decision based on theQoS request, such that it determines whether to activate or deactivatethe assigned carrier given to the AMS.

Hereinafter, this specification proposes a method for obviating anunnecessary scanning operation of an AMS, which performs communicationwith an ABS using multiple carriers, and obviating failure of a carrieractivation instruction of the ABS through a channel state measurementfor inactive carriers among secondary carriers assigned from the ABS.

First Exemplary Embodiment

The first exemplary embodiment illustrates a method for transmitting ascanning required indicator to an AMS to indicate whether or not to scana secondary carrier(s) assigned from an ABS (i.e., assigned secondarycarrier(s)) to obviate the AMS from executing an unnecessary scanning.

First, in the related art multicarrier operation, scanning for anassigned carrier from a serving ABS is performed by the ABS'sinstruction (AAI_SCN-RSP) or voluntarily by the AMS. Here, when the AMSvoluntarily performs the scanning for the assigned carrier, reportingfor the scan results, may be performed only when the ABS's instructionis received.

However, for the following cells in which multiple carriers arearranged, the AMS may unnecessarily perform scanning:

1. when multiple carriers belonging to an arbitrary ABS have the samecoverage

2. when multiple carriers belonging to an arbitrary ABS have differentcoverage.

FIG. 4( a) illustrates that multiple carriers belonging to an arbitraryABS have the same coverage, and FIG. 4( b) illustrates that multiplecarriers belonging to an arbitrary ABS have different coverage.

First, as illustrated in FIG. 4( a), when all the carriers belonging toan arbitrary ABS have the same coverage, the AMS does not have toperform scanning for measuring channel state information related to anassigned carrier. However, the related art method allows the AMS tovoluntarily perform scanning for a certain carrier, accordingly,unnecessary scanning for carriers with the same coverage is performed.

As illustrated in FIG. 4( b), when assigned secondary carriers assignedfrom the ABS have different coverage when the AMS performs a network(re)entry, the ABS may not recognize where the AMS is exactly locatedand fail to know a channel state(s) of an inactive carrier(s), whichcauses the ABS to instruct activation of a certain inactive carrier. Inthis case, if the corresponding carrier has smaller coverage than theexisting active carriers and the AMS is in the outside of the carrierwhose activation is instructed by the ABS, the ABS's activation for thecorresponding carrier may be failed.

Therefore, downlink (DL) carrier channel state information, such ascarrier to interference and noise ratio (CINR) for a secondary carriermay be measured for inactive carriers as well as active carriers, andthe measurement results needs to be transmitted to the ABS.

Definition of Scanning Required Indicator

Scanning required indicator or scanning required indication field istransmitted from ABS to AMS to indicate whether to scan a carrier(voluntarily by the AMS) or not when the corresponding carrier is usedas a secondary carrier and the corresponding carrier is inactive. Also,the scanning required indicator may be 1-bit in size for each carrier.

Also, the scanning required indicator may be transmitted when the ABSassigns assigned secondary carriers to the AMS. As one example, thescanning required indicator may be transmitted to the AMS via theAAI_MC-RSP message.

Here, the base station may decide whether to scan the assigned secondarycarrier or not on the basis of the coverage of each carrier. Thecoverage of each carrier is information that the ABS already knows, sothe ABS can inform the AMS of the scanning or non-scanning withreference to the coverage value.

The ABS may select a carrier, which has been informed via the scanningrequired indicator as a carrier for which scanning is not required, as atarget carrier of a carrier management without request for scanreporting from the AMS. Here, the carrier management may be a carrieractivation, a carrier deactivation, a primary carrier change or thelike.

The base station may recognize channel state (carrier to interferenceand noise ratio (CINR), received signal strength indicator (RSSI), roundtrip delay (RTD), etc.) information related to the assigned secondarycarrier, which has been informed via the scanning required indicator asa carrier for which scanning is not required, based on channel stateinformation related to a primary carrier. That is, the ABS may considerthe channel state information related to an assigned secondary carrier,informed as a scanning-unnecessary carrier, as the same as the channelstate information related to the primary carrier.

Transmission of Scanning Required Indicator

Hereinafter, description will be made to an exemplary format of MC-RSPmessage, MC-ADV message or NBR-ADV message each including the scanningrequired indicator defined in the first exemplary embodiment.

(1) Transmission Via AAI_MC-RSP Message

The following Table 1 shows an example that the scanning requiredindicator is included in AAI_MC-RSP message.

TABLE 1 Field Size (bit) Description Control Message Type 8 AAI_MC-RSPmessage Global_Assign 1 Indicates whether the ABS assigns all thecarriers requested by AMS through AAI_MC- REQ 0b0: The ABS assigns asubset of the carriers requested by AMS 0b1: The ABS assigns all thecarriers requested by AMS If(Global_Assign == 0){  Number of AssignedCarriers (N) 4  For (i=0; i<N; i++){  Physical Carrier Index 6 Thecarriers AMS can simultaneously support  Scanning required indicator 1Indicates whether the assigned carrier needs to perform the scanning forcarrier management when the carrier is inactive. 0b0: The AMS mayperform scanning for the corresponding carrier. 0b1: The AMS shall not(or doesn't need to) perform scanning for the corresponding carrierwithout any direction from ABS.  } } Support of data transmission over 10 = not support guard sub-carrier 1 = support

Referring to Table 1, the scanning required indicator field indicateswhether to perform scanning for carrier management when a correspondingcarrier is inactive. As one example, when the scanning requiredindicator field is set to ‘0b0,’ the AMS performs scanning for thecorresponding carrier. When set to ‘0b1’, the AMS shall not performscanning for the corresponding carrier without any direction from theABS.

The following Table 2 shows an example that a carrieractivation-specific (CA-specific) trigger condition field is included inMC-RSP message when the scanning required indicator is set to ‘0b1.’

TABLE 2 Field Size (bit) Note Global_Assign 1 Indicates whether the ABSassigns all the carriers requested by AMS through AAI_MC-REQ 0b0: TheABS assigns a subset of the carriers requested by AMS 0b1: The ABSassigns all the carriers requested by AMS If(Global_Assign == 0) {Number of Assigned 3 Number of assigned secondary carriers. Carriers (N)For (i=0; i<N; i++){ Physical carrier 6 The index refers to a physicalcarrier index in index AAI_MC-ADV message. Logical carrier index isassigned implicitly in the order of assigned physical carrier index.Scanning required 1 0: The AMS does not need to perform scanning whenindicator the carrier is inactive. 1: The AMS may perform scanningwithout any direction from ABS when the carrier is inactive. If(scanning required indicator ==1){ CM-specific Variables CM-specifictriggers with encoding defined in Table Trigger TLVs 9-12 Triggerdescription for assigned carriers. } } } Support of data 1 0 = notsupport transmission over 1 = support guard sub-carrier

The following Table 3 shows an example that CA-specific triggercondition field is included in MC-RSP message when the scanning requiredindicator is set to ‘0b1.’

TABLE 3 Attributes/Array M/0 of attributes Size (bit) Value/NoteConditions M Global Assign 1 Indicates whether the ABS assigns all thecarriers requested by AMS through AAI_MC-REQ 0b0: The ABS assigns asubset of the carriers requested by AMS 0b1: The ABS assigns all thecarriers requested by AMS 0 Number of 3 Indicates the number of carriersto be Shall be present assigned assigned to the MS when the Globalcarriers Assign is zero 0 Physical carrier 6 Indicates the carriers tobe assigned Shall be present index to the MS. Logical carrier index iswhen the Global assigned implicitly in the order of Assign is zeroassigned physical carrier index 0 Scanning 1 Indicates whether the AMSneeds Shall be required to perform the scanning the present whenindicator scanning procedure for the the Global assigned carrier whenthe carrier Assign is zero is inactive. 0: the AMS doesn't need toperform scanning. 1: The AMS may perform scanning without any directionfrom ABS. 0 CM-specific Variables CM-specific triggers with encodingShall be Trigger TLVs defined in Table 9-12 Trigger present whendescription for assigned carriers the scanning required indicator is setto 1. M Support of data 1 Indicates the support of guard carriertransmission for data over guard 0b0: not supported sub-carrier 0b1:supported

(2) Transmission Via AAI_MC-ADV Message

The following Table 4 shows an example that the scanning requiredindicator is included in AAI_MC-ADV message.

TABLE 4 Field Size (bit) Description MAC control Message Type 8multi-carrier configuration change 4 Incremented by 1 upon each updatecount Serving BS Carrier Number 3 Serving BS Uniformity Flag 1 0: AllCarriers supported by serving ABS have the same Protocol Version,SFH_Info 1: otherwise Physical Carrier Index of current 6 The carrierthat ABS broadcast this message; the physical carrier index refers tocarrier AAI_Global-Config message MAC Protocol version 8 Consistent withREV.2 definition, with new MAC protocol version 9 defined for 16mFor(i=1;i<=Serving BS Carrier Number−1; i++){ Physical carrier indexPaging carrier indication SA-Preamble Index  Scanning required indicator1 Indicates whether the assigned carrier needs to perform the scanningfor carrier management when the carrier is inactive. 0b0: The AMS mayperform scanning for the corresponding carrier. 0b1: The AMS shall not(Or doesn't need to) perform scanning for the corresponding carrierwithout any direction from ABS. if (Serving BS Uniformity Flag==1) {    omitted Protocol version, SFH information for neighbor ABS }

(3) Transmission Via Neighbor Advertisement (AAI_NBR-ADV) Message

The following Table 5 shows an example that the scanning requiredindicator is included in AAI_NBR-ADV message.

TABLE 5 Attributes/Array Size M/O of attributes (bit) Value/NoteConditions M Change Count 3 NBR-ADV Change Coutn N.A. M Cell Type 3 Celltype in this message N.A. 0b000: macro, 0b001: micro, 0b010: macrohotzone, 0b011: femto, 0b100: relay, 0b101-0b111: reserved M TotalNumber of 4 Total number of segments of AAI_NBR-ADV for this cell type.N.A. AAI_NBR-ADV Segments M AAI_NBR-ADV 4 Indicates current segmentindex of this N.A. Segment Index message in the specific cell type. M BSnumber M 8 Total number of BSs to be included in this AAI_NBR-ADVsegment N.A. . . . omitted . . . O Delta information Var. Deltaencoding, w.r.t. the reference carrier the current carrier Shall beincluded for each transmitting this message if SFH_encoding format = 01,the neighbor BS if preceding carrier if SFH_encoding_format = 11)SFH_encoding_format is set to 0b01 or 0b11 O Neighbor-specific Var.Optional neighbor-specific triggers with encoding May be included foreach trigger defined in Trigger description neighbor BS O Scanningrequired 1 Indicates whether the carrier needs to perform the scanningfor May be included for each indicator carrier management when thecarrier is inactive. neighbor BS 0b0: The AMS may perform scanning forthe corresponding carrier. 0b1: The AMS shall not (or doesn't need to)perform scanning for the corresponding carrier without any directionfrom ABS. . . . following fields omitted . . .

FIG. 5 is flowchart illustrating a method for performing a scanningoperation using a scanning required indicator in accordance with a firstexemplary embodiment.

As illustrated in FIG. 5, an ABS may transmit a message including ascanning required indicator indicating whether to scan a specificcarrier or not to an AMS (S501).

Here, the message, as aforementioned, may be MC-RSP message, MC-ADVmessage or NBR-ADV message.

When the scanning required indicator is transmitted via the MC-RSPmessage, it is included in the MC-RSP message together with an assignedsecondary carrier to be sent to the AMS when the ABS assigns thecorresponding assigned secondary carrier to the AMS.

The scanning required indicator or scanning required indication fieldmay be transmitted by being included in the message when the specificcarrier is used as a secondary carrier and the corresponding carrier isinactive. Also, the scanning required indicator may be 1-bit in size foreach carrier.

Afterwards, the AMS may perform scanning only for a carrier whosescanning required indicator is set to ‘0b1’ (S502).

The AMS may then report the scan results to the ABS (S503). Here, thescan results may be transmitted to the ABS via a scan report message.

FIG. 6 is a flowchart illustrating a method for performing scanningusing a scanning required indicator and carrier activation-specific(CA-specific) trigger condition as another example according to thefirst exemplary embodiment.

As illustrated in FIG. 6, an ABS may transmit to an AMS a scanningrequired indicator indicating whether to scan a specific carrier or notand a CA-specific trigger condition (S601).

Here, the CA-specific trigger condition may be transmitted to the AMS bybeing included in the message when the scanning required indicator isset to ‘0b1.’ Here, the message, as aforementioned, may be MC-RSPmessage, MC-ADV message or NBR-ADV message.

When a metric of channel state information (CINR, RSSI, RTD) measuredfrom the carrier having the scanning required indicator set to ‘0b1’satisfies a scanning initiation condition of the CA-specific triggercondition (S602), then the AMS may perform scanning for thecorresponding carrier (S603).

Afterwards, when the scan results satisfy a scan reporting condition ofa multicarrier-specific (MC-specific) trigger condition and accordinglythe AMS triggers the scan reporting to the ABS (S604), the AMS maytransmit a scan reporting (SCN-REP) message to the ABS by includingcarrier to interference and noise ratio (CINR), received signal strengthindicator (RSSI), round trip delay (RTD) and the like, which aremeasured through the scanning (i.e., the scan results) (S605).

Second Exemplary Embodiment

The second exemplary embodiment illustrates a method for informingwhether to scan a corresponding carrier according to presence ornon-presence of the same value as a newly defined multicarrier-specific(MC-specific) trigger when a trigger condition (e.g., the MC-specifictrigger) for carrier management is newly defined.

That is, in the second exemplary embodiment, in case where a triggercondition for carrier management is newly defined (e.g., MC-specifictrigger or CA-specific trigger) and the defined value is transmitted viaa broadcast message, such as AAI_MC-ADV or AAI_NBR-ADV, for a carrierfor which scanning can be skipped due to having the same coverage as areference carrier (or with other various reasons), whether to scan thecorresponding carrier or not may be informed according to presence ornon-presence of the same value as the MC-specific trigger to betransmitted via the broadcast message.

Here, the reference carrier may be the first carrier in AAI_MC-ADVmessage or AAI_NBR-ADV message.

Hereinafter, trigger conditions defined for the carrier management(secondary carrier activation) will be described.

1. Scanning Trigger Condition for Secondary Carrier Activation

A scanning trigger condition proposed in this specification is whetheror not a corresponding inactive carrier is receivable from the currentperspective of an AMS.

That is, such trigger condition is required only for a carrier havingsmaller coverage than a primary carrier because a zone of a carrierhaving larger coverage generally includes a zone of a carrier havingsmaller coverage.

(1) Trigger Condition 1

As described above, availability of a carrier having small coverageincreases as an AMS moves toward the center of a cell. That is, a casewhere a value, such as power, SINR (or CINR), RSSI or the like, of aprimary carrier is more than a specific value may be considered as themost easily useable trigger condition.

The ABS already knows coverage information about each of the twocarriers, so it may inform the AMS to initiate scanning when a specificvalue is more than a preset value based on the primary carrier. Sincethis value should be decided from the perspective of the ABSirrespective of a receiver capability, values such as signal power orRSSI may be used for trigger.

When a corresponding trigger value meets a trigger condition of aspecific secondary carrier as the AMS enters the center of the cell,scanning for the corresponding secondary carrier may be initiated.

(2) Trigger Condition 2

On the contrary, even when the AMS moves from an available zone into anon-available zone, if the corresponding trigger value becomes less thana specific value, scanning may be initiated.

2. Scan Reporting Trigger Condition for Secondary Carrier Activation

When scanning is initiated according to the trigger condition 1, whenthe scanned value is greater than a specific value, the AMS may reportthis information to the ABS so as to inform the ABS of whether or notthe current carrier is available.

On the contrary, when scanning is initiated according to the triggercondition 2, if the scanned value is less than the specific value, theAMS may report the information to the ABS so as to inform the ABS ofwhether the current carrier is available. The AMS may report the scanresults to the ABS periodically or one time under a satisfactorysituation.

Whether to be available/non-available may be decided based on a commonvalue (e.g., RSSI, signal power) or the like, or be affected by thenumber of reception antennas of the AMS, receiver capability or the likedue to being a value related to actual transmission and reception. Here,whether to be available/non-available may thusly be decided based uponan actual reception capability by using a value of SINR, CINR or thelike.

If decided based on the reception capability, the same trigger conditionvalue may be used for every carrier in a whole cell. In this case,overhead due to a trigger condition transmission may be reduced.

Hence, the ABS may check whether or not a specific secondary carrier canbe activated based upon the AMS's reporting.

Also, in a deactivation of a specific secondary carrier, whether to beavailable may be checked based on feedback such as CQI of an activecarrier or the like.

When the AMS reports the scan results to the ABS one time, the reportingof the scan results may be a scanning release condition.

Consequently, each carrier may require two trigger conditions and alsotwo report conditions. The report condition may be defined by two foreach network, or instead of defining two report conditions, a centervalue may be defined and then two report conditions may be inferred byincreasing (+) or decreasing (−) a predetermined margin.

FIG. 7 illustrates trigger values for scanning and scan reportingaccording to power of a primary carrier and SINR of a secondary carrierwhen an AMS moves toward the center of a cell under the triggercondition 2 of the second exemplary embodiment.

FIG. 8 illustrates trigger values for scanning and reporting accordingto power of a primary carrier and SINR of a secondary carrier when anAMS moves away from the center of a cell under the trigger condition 1of the second exemplary embodiment.

The following Table 6 shows an example that a multicarrier-specific(MC-specific) trigger field for carrier management is included inAAI_NBR-ADV message.

TABLE 6 Attributes/Array of M/O attributes Size (bit) Value/NoteConditions M Change Count 3 NBR-ADV Change Coutn N.A. M Cell Type 3 Celltype in this message N.A. 0b000: macro, 0b001: micro, 0b010: macrohotzone, 0b011: femto, N.A. 0b100: relay, 0b101-0b111: reserved M TotalNumber of 4 Total number of segments of AAI_NBR-ADV for this cell type.N.A. AAI_NBR- ADV Segment M AAI_NBR- 4 Indicates current segment indexof this message in the N.A. ADV Segment specific cell type. Index M BSnumber M 8 Total number of BSs to be included in this AAI_NBR-ADVsegment N.A. . . . omitted . . . O Delta information Var. Deltaencoding, w.r.t. the reference carrier the current carrier Shall boincluded for each transmitting this message if SFH_encoding format = 01,the neighbor BS if preceding carrier if SFH_encoding_format = 11)SFH_encoding_format is set to 0b01 or 0b11 O Neighbor-specific Var.Optional neighbor-specific triggers with encoding May be included foreach trigger defined in Trigger description neighbor BS O MC-specifictrigger Var. MC-specific triggers with encoding defined in Table 9-12May be included for Trigger description for assigned carriers availablecarriers of If MC-specific trigger is transmitted for a carrier, the AMSeach neighbor BS. shall perform any action triggered by the encoding.Else, the AMS doesn't need to perform any action for this carrier andrefers to the measurement results of the reference carrier (i.e.,previous carrier). . . . following fields omitted . . .

Referring to Table 6, the MC-specific trigger field refers to anMC-specific trigger with encoding defined in Tables 9-12 showing triggerconditions for assigned carriers.

If the MC-specific trigger is transmitted to the AMS for a specificcarrier, the AMS may perform a certain action triggered by the encoding.Else, the AMS does not need to perform a specific action for the carrierand may refer to the measurement results of the reference carrier (e.g.,previous carrier).

The following Table 7 shows an example that an MC-specific trigger fieldfor carrier management is included in AAI_MC-ADV message.

TABLE 7 Field Size (bit) Description MAC control Message Type 8Multi-carrier configuration 4 Incremented by 1 upon each update changecount Serving BS Carrier Number 3 Serving BS Uniformity Flag 1 0: AllCarriers supported by serving ABS have the same Protocol Version,SFH_Info 1: otherwise Physical Carrier Index of current 6 The carrierthat ABS broadcast this message; the physical carrier index refers tocarrier AAI_Global-Config message MAC Protocol version 8 Consistent withREV.2 definition, with new MAC protocol version 9 defined for 16mFor(i=1;i<=Serving BS Carrier Number−1; i++){ Physical carrier indexPaging carrier indication SA-Preamble Index If (Same coverage asreference carrier!){ MC-specific Trigger TLV variables MC-specifictriggers with encoding defined in Table 9-12 Trigger description forassigned carriers If MC-specific trigger is transmitted for a carrier,the AMS shall perform the action triggered by this encoding. Else, theAMS doesn't need to perform any action for this carrier and just refersto the measurement results of the reference carrier (i.e., previouscarrier) } if(Serving BS Uniformity Flag==1) {      omitted Protocolversion, SFH information for neighbor ABS }

Third Exemplary Embodiment

The third exemplary embodiment illustrates a method for defining atrigger condition for carrier management (e.g., secondary carrieractivation or primary carrier change) and transmitting a messageincluding the defined trigger condition.

First, prior to the method proposed in the third exemplary embodiment,it is allowed to define a trigger condition for measuring a channelstate of a specific carrier of a neighbor ABS for performing handover(HO) via AAI_SCD message.

However, the previous method defines scanning for a carrier belonging toa serving ABS (serving cell) to be performable through SCN-REQ/RSP/REPmessage processes according to the ABS's direction, but does notseparately define a trigger condition for scanning for multiplesecondary carriers.

That is, regarding the related scanning operation, even if the AMSrecognizes based on a specific metric that a channel state of a targetcarrier becomes better, a channel state measurement for thecorresponding carrier may not be performed.

Furthermore, even if scanning is performed, the AMS reports the scanresults (i.e., transmits SCN-REP) to the ABS only when receiving SCN-RSPfrom the ABS. That is, the channel state information related to anycarrier within a cell is transmitted by the AMS only in response to theABS's request.

Here, when a carrier management with respect to the AMS is required, theABS requests scanning from the AMS, receives the scan result from theAMS, and performs the carrier management. This causes a delay of acarrier management related procedure, which may be performed for amulticarrier operation.

Also, as described above, if the ABS voluntarily instructs a carriermanagement (e.g., activation of assigned secondary carrier) with respectto the AMS without requesting scanning from the AMS, a target carrier israndomly selected in a state of a channel state of the target carrierbeing unknown. Accordingly, when the channel state of the target carrieris bad, a carrier management failure or inefficient carrier managementmay be caused.

Hereinafter, description will be made in detail to the method ofdefining a trigger condition for carrier management (e.g., secondarycarrier activation) and transmitting the defined trigger condition inaccordance with the third exemplary embodiment.

1. Scanning for Assigned Carriers by AMS

A scanning operation may provide the AMS with an opportunity ofmeasuring assigned carriers for carrier management (e.g., secondarycarrier activation or primary carrier change) and acquiring necessarysystem configuration information.

When the AMS has a multicarrier aggregation capability, the AMS mayperform measurement for assigned carriers without a time intervalspecific for scanning.

The ABS may clarify trigger parameter values based on target carrierswithin a SCD message (or MC-ADV message, NBR-ADV message, SFH or MC-RSPmessage). Also, the ABS may clarify a (fully configured or partiallyconfigured) form of a target carrier, which the AMS is to scan, and/oraveraging parameters, which are obtained by overriding values defined inthe SCD message.

Here, a trigger condition used for carrier management, unlike a triggercondition used for handover (HO), may be information, which the AMSshould receive as soon as possible after a network reentry. Therefore,the trigger condition used for the carrier management may preferably betransmitted via a different message or a superframe header (SFH), otherthan transmitted via AAI_SCD message.

If a trigger condition defined for carrier management is transmitted viaAAI_SCD (or SHF, AAI_MC-ADV) message and information related to AAI_SCDmessage of a neighbor ABS is different from AAI_SCD information of aserving ABS, the AAI_SCD information of the neighbor ABS may preferablybe transmitted via AAI_NBR-ADV.

If assigned secondary carriers assigned from the base station cannot besimultaneously scanned due to the limitation to the AMS capability, theAMS should receive a time interval assigned from the base station. Inthis case, the scanning procedure for the assigned carriers may beperformed by the AMS as follows.

When the ABS is unable to simultaneously perform a channel statemeasurement for an assigned carrier and an active carrier due to thelimitation to the AMS capability, the ABS may assign a time interval tothe AMS such that the AMS monitors other carriers.

2. Definition of Trigger Condition for Assigned Carrier

(1) Conditions defined when AMS starts scanning

(2) Conditions defined when AMS reports scan results to serving ABS

(3) Conditions defined when AMS attempts to initiate a primary carrierchange by transmitting a carrier management request message

-   -   Upon defined such that the AMS initiates a carrier management        (e.g., a secondary carrier management or a primary carrier        change), the AMS may transmit a carrier management request        (AAI_CM-REQ) message for a carrier management process request to        the ABS, and the carrier management request message may allow        the ABS to transmit a carrier management command (AAI_CM-CMD)        message.

(4) Conditions defined when a target carrier is unreachable

(5) Conditions defined when AMS is unable to maintain communication withthe current active carrier

(6) Conditions for carrier management cancellation

Definition of MC-Specific Trigger Condition (or CA-Specific TriggerCondition)

A handover (HO)-related trigger condition for performing the HO istransmitted from the ABS to the AMS via a system configuration descript(SCD) message.

Here, when the ABS transmits an MC-specific trigger condition orCA-specific trigger condition to the AMS via AAI_SCD message, suchtrigger condition may be defined as a different condition from theHO-related trigger condition.

To distinguish the MC-specific trigger condition from the HO-relatedtrigger condition, the MC-specific trigger condition may be transmittedvia AAI_MC-ADV message, AAI_NBR-ADV message, AAI_MC-RSP message or SFH,as well as via the SCD message.

The MC-specific trigger condition may be defined to be ABS-specific,carrier-specific or network-specific.

First, the following Table 8 shows an example of items included inMC-specific trigger control information (condition).

TABLE 8 Name Length (bits) Value Number of 2 The number of conditionsthat are included in this conditions trigger (see loop definitionbelow). When more than one condition is included, this trigger isreferred to as a complex trigger and is the logical AND combination ofall the included conditions. For(i=0; i<=Number of conditions; i++){Type/Function/Action 5 See following Table 9-12 for description Triggervalue 8 Trigger value is the value used in comparing measured metric fordetermining a trigger condition. Trigger averaging 4 The averagingparameter used for averaging this parameter trigger metric according toequation (1) for target ABS (which is defined in ABS type). If notpresent, the default trigger averaging parameter in AAI_SCD is used.0x0: 1 0x1: ½ 0x2: ¼ 0x3: ⅛ 0x4: 1/16 0x5: 1/32 0x6: 1/64 0x7: 1/1280x8: 1/256 0x9: 1/512 0xA to 0xF: reserved }

The following Table 9 shows an example of Type/Function/Action item ofthe items included in the MC-specific trigger control information ofTable 8.

TABLE 9 Size Name (bits) Value Description Type 2(MSB) Trigger metrictype: 0x0: CINR metric 0x1: RSSI metric 0x2: RTD metric 0x3: reservedFunction 2 Computation defining scanning and reporting triggercondition: 0x0: Metric of primary carrier is greater than absolute value0x1: Metric of primary carrier is less than absolute value 0x2: Metricof secondary carrier is greater than absolute value 0x3: Metric ofsecondary carrier is less than absolute value Action 1(LSB) Actionperformed upon reaching Action 0b0 trigger condition: applies to only0b0: Initiate the scanning Function 0x0 and 0b1: Respond on trigger with0x1, and action AAI_SCN-REP 0b1 applies to only Function 0x2 and 0x3.

The following Table 10 shows another example of Type/Function/Actionitem of the items included in the MC-specific trigger controlinformation of Table 8.

TABLE 10 Name Size (bit) Value Type TBD Trigger metric type: (MSB) 0x0:CINR metric, 0x1: RSSI metric, 0x2: RTD metric, 0x3: Metirc = number ofconsecutive P-SFHs missed, 0x4: RD metric, 0x5~0x7: reserved FunctionTBD Computation defining trigger condition: 0x0: Reserved 0x1: Metric ofassigned carrier is greater than absolute value 0x2: Metric of assignedcarrier is less than absolute value 0x3: Metric of assigned carrier isgreater than primary carrier metric by relative value 0x4: Metric ofassigned carrier is less than primary carrier metric by relative value0x5: Metric of active (or primary) carrier greater than absolute value0x6: Metric of active (or primary) carrier less than absolute value 0x7:Reserved NOTE: 0x1~0x4 not applicable for RTD trigger metric NOTE: whentype 0x1 is used together with function 0x3 or 0x4. the threshold valueshall range from 32 dB (0x80) to +31.75 dB(0x7F). When type 0x1 is usedtogether with function 0x1, 0x2, 0x5 or 0x6, the threshold value shallbe interpreted as an unsigned byte with units of 0.25 dB, such that 0x00is interpreted as −103.75 dBm and 0xFF is interpreted as −40 dBm NOTE:Type 0x3 can only be used together with function 0x5 or function 0x6.Action TBD Action performed upon reaching trigger condition: (MSB) 0x0:Reserved 0x1: Respond on trigger with AAI_SCN-REP 0x2: Respond ontrigger with AAI_CM-REQ 0x3: Respond on trigger with AAI_SCN-REQ 0x4:Declare the carrier unreachable. If the carrier is a target carrier, theAMS needs not take immediate action when this trigger condition is met.The AMS shall act only when this condition is met for all assignedcarriers of the AMS. 0x5: Cancel Carrier Management 0x6: InitiateScanning 0x7: Reserved

Referring to Table 10, the MC-specific trigger condition information mayinclude a type field indicating a trigger metric type. The type field,as one example, indicates CINR metric when set to ‘0x0,’ RSSI metricwhen set to ‘0x1,’ RTD metric when set to ‘0x2,’ the number of timesthat P-SFHs are not consecutively received (number of consecutive P-SFHsmissed) when set to ‘0x3,’ and RD metric when set to ‘0x4.’

Also, the MC-specific trigger condition information may include afunction field indicating computation defining a trigger condition. Asone example, upon the function field being set to ‘0x1,’ the triggercondition is met when a metric of an assigned carrier is greater than anabsolute value (or threshold value). Upon set to ‘0x2,’ the triggercondition is met when a metric of an assigned carrier is less than anabsolute value. Upon set to ‘0x3,’ the trigger condition is met when ametric of an assigned carrier is greater than a metric of a primarycarrier by a relative value. Upon set to ‘0x4,’ the trigger condition ismet when a metric of an assigned carrier is less than a metric of aprimary carrier by a relative value. Upon set to ‘0x5,’ the triggercondition is met when a metric of an active (or primary) carrier isgreater than an absolute value. Upon set to ‘0x6,’ the trigger conditionis met when a metric of an active (or primary) carrier is less than anabsolute value.

The MC-specific trigger control information may further include anaction field, which is performed when reaching a trigger condition.

As one example, if the action field is set to ‘0x1,’ the AMS transmits ascan reporting (SCN-REP) message with respect to the scan results to theABS when a trigger condition is met. If set to ‘0x2,’ the AMS transmitsa carrier management request (CM-REQ) message to the ABS when thetrigger condition is met. If set to ‘0x3,’ the AMS transmits a scanrequest (SCN-REQ) message to the ABS when the trigger condition is met.If set to ‘0x4,’ it indicates that the corresponding carrier isunreachable. If set to ‘0x5,’ it indicates a carrier managementcancellation. If set to ‘0x6,’ scanning for an assigned carrier isinitiated when the trigger condition is met.

The following Table 11 shows another example of Type/Function/Actionitem of the items included in the MC-specific trigger controlinformation of Table 8.

Especially, Table 11 shows an example of merely defining values requiredfor MC-specific trigger condition for carrier management. That is,function and action fields, as shown in Table 11, may be defined bymerely including values required for carrier management.

TABLE 11 Name Size (bit) Value Type TBD Trigger metric type: (MSB) 0x0:CINR metric 0x1: RSSI metric 0x2: RTD metric, 0x3: Metirc = number ofconsecutive P-SFHs missed 0x4: RD metric, 0x5~0x7: reserved Function TBDComputation defining trigger condition: 0x0: Reserved 0x1: Metric ofassigned carrier is greater than absolute value 0x2: Metric of assignedcarrier is greater than primary carrier metric by relative value 0x3:Metric of active (or primary) carrier less than absolute value 0x4-0x7:Reserved NOTE: 0x1~0x2 not applicable for RTD trigger metric NOTE: whentype 0x1 is used together with function 0x3 or 0x4. the threshold valueshall range from 32 dB (0x80) to +31.75 dB(0x7F). When type 0x1 is usedtogether with function 0x1, 0x2, 0x5 or 0x6, the threshold value shallbe interpreted as an unsigned byte with units of 0.25 dB, such that 0x00is interpreted as −103.75 dBm and 0xFF is interpreted as −40 dBm NOTE:Type 0x2 can only be used together with function 0x3. Action TBD Actionperformed upon reaching trigger condition: (MSB) 0x0: Reserved 0x1:Respond on trigger with AAI_SCN-REP 0x2: Respond on trigger withAAI_SCN-REQ 0x3: Initiate Scanning 0x4-0x7: Reserved

If the trigger condition proposed in this specification is transmittedvia a message different from AAI_SCD message for transmitting theHO-related trigger condition, it may be allowed that the triggercondition is used the same as the HO-related trigger condition butinterpreted as different meaning.

The following Table 12 shows another example of Type/Function/Actionitem of the items included in the MC-specific trigger controlinformation of Table 8.

TABLE 12 Name Size (bit) Value Type TBD Trigger metric type: (MSB) 0x0:CINR metric, 0x1: RSSI metric, 0x2: RTD metric, 0x3: Metirc = number ofconsecutive P-SFHs missed, 0x4: RD metric, 0x5~0x7: reserved FunctionTBD Computation defining trigger condition: 0x0: Reserved 0x1: Metric ofneighbor ABS (assigned carrier) is greater than absolute value 0x2:Metric of neighbor ABS (assigned carrier) is less than absolute value0x3: Metric of neighbor ABS (assigned carrier) is greater than servingABS (primary carrier) metric by relative value 0x4: Metric of neighborABS (assigned carrier) is less than serving ABS (primary carrier) metricby relative value 0x5: Metric of serving ABS (active or primary carrier)greater than absolute value 0x6: Metric of serving ABS (active orprimary carrier) less than absolute value 0x7: Reserved NOTE: 0x1~0x4not applicable for RTD trigger metric NOTE: when type 0x1 is usedtogether with function 0x3 or 0x4. the threshold value shall range from32 dB (0x80) to +31.75 dB(0x7F). When type 0x1 is used together withfunction 0x1, 0x2, 0x5 or 0x6, the threshold value shall be interpretedas an unsigned byte with units of 0.25 dB, such that 0x00 is interpretedas −103.75 dBm and 0xFF is interpreted as −40 dBm NOTE: Type 0x3 canonly be used together with function 0x5 or function 0x6. Action TBDAction performed upon reaching trigger condition: (MSB) 0x0: Reserved0x1: Respond on trigger with AAI_SCN-REP 0x2: Respond on trigger withAAI_HO-REQ (AAI_CM-REQ) 0x3: Respond on trigger with AAI_SCN-REQ 0x4:Declare the carrier unreachable. If the carrier is a target carrier, theAMS needs not take immediate action when this trigger condition is met.The AMS shall act only when this condition is met for all assignedcarriers of the AMS. 0x5: Cancel HO (Carrier Management) 0x6: InitiateScanning 0x7: Reserved NOTE: 0x3 is not applicable when neighbor ABSmetrics are defined (i.e., only Function valued 0x5 or 0x6 areapplicable)

As shown in Tables 8 to 12, when metrics of channel state information(CINR, RSSI, RTD), which the AMS measures from assigned secondarycarriers, meet a scan initiating condition of the MC-specific triggercontrol information, the AMS initiates scanning for the assignedsecondary carriers. Here, the AMS may perform scanning for the assignedsecondary carriers (including inactive secondary carriers) when the scantrigger condition is met even without a scan response messagetransmitted from the ABS if necessary.

Also, when the scan results meet the scan reporting condition of theMC-specific trigger control information so as to trigger a scanreporting to the ABS, the AMS may transmit to the ABS CINR, RSSI, RTDand the like measured through the scanning (i.e., scan results) via theSCN-REP message.

Method for Transmitting MC-Specific Trigger Condition

Hereinafter, description will be made to each exemplary embodiment oftransmitting the aforesaid MC-specific trigger control information(condition) from ABS to AMS via a particular message.

1. Transmission of MC-Specific Trigger Condition Via AAI_MC-ADV Message

(1) When MC-Specific Trigger Condition is ABC-Specific

The following Table 13 shows an example that the MC-specific triggercondition is transmitted via MC-ADV message and is ABS-specific.

TABLE 13 Field Size Description MAC control Message Type 8 Multicarrierconfiguration 4 Incremented by 1 upon each update change count ServiceBS Carrier Number 3 Serving BS Uniformity Flag 1 0: All carrierssupported by serving ABS have the same Protocol Version, SFH_Info 1:otherwise Physical Carrier Index of 6 The carrier that ABS broadcastthis message; current carrier the physical carrier index refers toAAI_Global-Config message. MAC Protocol version 8 Consistent with REV.2definition, with new MAC protocol version 9 defined for 16m MC-specificTrigger TLV variables MC-specific triggers with encoding defined inTable 9-12 Trigger description for assigned carriers . . .

(2) When MC-Specific Trigger Condition is Carrier-Specific

The following Table 14 shows an example that the MC-specific triggercondition is transmitted via MC-ADV message and is carrier-specific.

TABLE 14 Field Size Description MAC control Message Type 8 Multicarrierconfiguration 4 Incremented by 1 upon each update change count ServiceBS Carrier Number 3 Serving BS Uniformity Flag 1 0: All carrierssupported by serving ABS have the same Protocol Version, SFH_Info 1:otherwise Physical Carrier Index of 6 The carrier that ABS broadcastthis message; current carrier the physical carrier index refers toAAI_Global-Config message. MAC Protocol version 8 Consistent with REV.2definition, with new MAC protocol version 9 defined for 16mFor(i=1;i<=Serving BS Carrier Number−1; i++){ Physical carrier indexPaging carrier indication SA-Preamble Index MC-specific Trigger TLVvariables MC-specific triggers with encoding defined in Table 9-12Trigger description for assigned carriers

(3) When MC-Specific Trigger Condition is Network-Specific

The following Table 15 shows an example that MC-specific triggercondition is transmitted via MC-ADV message and is network-specific. Inthis case, the same trigger condition may be used in every cell and atrigger metric type used may be CINR.

TABLE 15 Field Size Description MAC control Message Type 8 Multicarrierconfiguration 4 Incremented by 1 upon each update change count ServiceBS Carrier Number 3 Serving BS Uniformity Flag 1 0: All carrierssupported by serving ABS have the same Protocol Version, SFH_Info 1:otherwise Physical Carrier Index of 6 The carrier that ABS broadcastthis current carrier message; the physical carrier index refers toAAI_Global-Config message. MAC Protocol version 8 Consistent with REV.2definition, with new MAC protocol version 9 defined for 16mFor(i=1;i<=Serving BS Carrier Number−1; i++){ Physical carrier indexPaging carrier indication SA-Preamble Index MC-specific Trigger TLVvariables MC-specific triggers with encoding defined in Table 9-12Trigger description for assigned carriers

2. Transmission of MC-Specific Trigger Condition Via AAI_NBR-ADV Message

(1) When MC-Specific Trigger Condition is ABS-Specific

The following Table 16 shows an example that MC-specific triggercondition is transmitted via NBR-ADV message and is ABS-specific.

TABLE 16 Attributes/Array M/O of attributes Size (bit) Value/NoteConditions M Change Count 3 NBR-ADV Change Coutn N.A. M Cell Type 3 Celltype in this message N.A. 0b000: macro, 0b001: micro, 0b010: macrohotzone, 0b011: femto, 0b100: relay, 0b101-0b111: reserved M TotalNumber of 4 Total number of segments of AAI_NBR-ADV for this cell type.N.A. AAI_NBR-ADV Segments M AAI_NBR-ADV 4 Indicates current segmentindex of this message in the specific cell type. N.A. Segment Index M BSnumber M 8 Total number of BSs to be included in this AAI_NBR-ADVsegment N.A. . . . omitted . . . O Delta information Var. Deltaencoding, w.r.t. the reference carrier the current carrier Shall beincluded for each transmitting this message if SFH_encoding format = 01,the preceding neighbor BS if carrier if SFH_encoding_format = 11)SFH_encoding_format is set to 0b01 or 0b11 O Neighbor-specific Var.Optional neighbor-specific triggers with encoding May be included foreach trigger defined in Trigger description neighbor BS O Neighbor MC-Var. Optional neighbor MC-specific triggers with encoding May beincluded for each specific trigger defined in Table 9-12 Triggerdescription neighbor BS . . . following fields omitted . . .

(2) When MC-Specific Trigger Condition is Carrier-Specific

The following Table 17 shows an example that the trigger condition istransmitted via NBR-ADV message and is carrier-specific.

TABLE 17 Attributes/Array M/O of attributes Size (bit) Value/NoteConditions M Change Count 3 NBR-ADV Change Coutn N.A. M Cell Type 3 Celltype in this message N.A. 0b000: macro, 0b001: micro, 0b010: macrohotzone, 0b011: femto, 0b100: relay, 0b101-0b111: reserved M TotalNumber of 4 Total number of segments of AAI_NBR-ADV for this cell type.N.A. AAI_NBR-ADV Segments M AAI_NBR-ADV 4 Indicates current segmentindex of this message in the specific cell type. N.A. Segment Index M BSnumber M 8 Total number of BSs to be included in this AAI_NBR-ADVsegment N.A. . . . omitted . . . O Delta information Var. Deltaencoding, w.r.t. the reference carrier the current carrier Shall beincluded for each transmitting this message if SFH_encoding format = 01,the preceding neighbor BS if carrier if SFH_encoding_format = 11)SFH_encoding_format is set to 0b01 or 0b11 O Neighbor-specific Var.Optional neighbor-specific triggers with encoding May be included foreach trigger defined in Trigger description neighbor BS O Neighbor MC-Var. Optional neighbor MC-specific triggers with encoding May beincluded for each specific trigger defined in Table 9-12 Triggerdescription carrier of neighbor BS . . . following fields omitted . . .

3. Transmission of MC-Specific Trigger Condition Via MC-RSP Message

(1) When MC-Specific Trigger Condition is ABS-Specific

The following Table 18 shows an example that the trigger condition istransmitted via MC-RSP message and is ABS-specific.

TABLE 18 Field Size (bit) Description Global_Assign 1 Indicates whetherthe ABS assigns all the carriers requested by AMS through AAI_MC-REQ0b0: The ABS assigns a subset of the carriers requested by AMS 0b1: TheABS assigns all the carriers requested by AMS If (Global_Assign == 0) { Number of Assigned Carriers (N) 3 Number of Assigned SecondaryCarriers.  For (i=0; i<N; i++) {  Physical carrier index 6 The indexrefers to a Physical carrier index in AAI_MC-ADV message. Logicalcarrier index is assigned implicitly in the order of assigned physicalcarrier index  } } MC-specific Trigger TLV variables MC-specifictriggers with encoding defined in Table 9-12 Trigger description forassigned carriers Support of data transmission over 0 = not supportguard sub-carrier 1 = support

(2) When MC-Specific Trigger Condition is Carrier-Specific

The following Table 19 shows an example that the trigger condition istransmitted via MC-RSP message and is carrier-specific.

TABLE 19 Field Size (bit) Description Global_Assign 1 Indicates whetherthe ABS assigns all the carriers requested by AMS through AAI_MC-REQ0b0: The ABS assigns a subset of the carriers requested by AMS 0b1: TheABS assigns all the carriers requested by AMS If (Global_Assign == 0) { Number of Assigned Carriers (N) 3 Number of Assigned Secondary Carriers For (i=0; i<N; i++) {  Physical carrier index 6 The index refers to aPhysical carrier index in AAI_MC-ADV message. Logical carrier index isassigned implicitly in the order of assigned physical carrier indexMC-specific Trigger TLV variables MC-specific triggers with encodingdefined in Table 9-12 Trigger description for assigned carriers  } }Support of data transmission over 0 = not support guard sub-carrier 1 =support

FIG. 9 illustrates a method for reporting scan results of assignedsecondary carriers via MC-ADV message including specific triggerconditions in accordance with a third exemplary embodiment.

As illustrated in FIG. 9, it is assumed that an ABS uses three carriersC_(—)0 to C_(—)2 as available carriers, the carrier C_(—)0 of the threecarriers is set to a primary carrier, and the others are set to assignedsecondary carriers (i.e., a completed state of AAI_MC-REQ/RSP messageexchange between ABS and AMS). Here, it is also assumed that the otherassigned carriers C_(—)1 and C_(—)2 are inactive assigned secondarycarriers. So, hereinafter, description will be made to a carrierscanning related operation for activating the carriers C_(—)1 andC_(—)2.

First, the AMS may exchange control information and data with the ABSvia the primary carrier C_(—)0 (S901).

The ABS may transmit a multicarrier advertisement (AAI_MC-ADV) messageincluding trigger control information related to carrier management(e.g., secondary carrier activation or primary carrier change) to theAMS (S902).

Here, the carrier management related trigger control information mayinclude trigger conditions, such as an assigned secondary carrierscanning trigger condition and a scan reporting trigger condition. Also,the carrier management related trigger control information mayalternatively be transmitted via AAI_SCD message, AAI_MC-ADV message,AAI_NBR-ADV message, SFH or the like.

Here, when the carrier management related trigger control informationincludes the assigned secondary carrier scanning trigger condition, theAMS may perform scanning for the assigned secondary carriers if thescanning trigger condition set in the carrier management related triggercontrol information is met even without receiving a scan response(SCN-RSP) message from the ABS.

The base station, if necessary, may also instruct the AMS to performscanning for the assigned secondary carriers by transmitting the SCN-RSPmessage to the AMS.

Accordingly, the AMS performs scanning for the carriers C_(—)1 andC_(—)2 (S903). When the scan results meet the condition set in thecarrier management related trigger control information (S904), then theAMS reports the scan results to the ABS. Here, the AMS may transmit thescan results to the ABS via SCN-REP message (S905).

Afterwards, the ABS may refer to the scan results transmitted from theAMS to transmit a carrier management command (AAI_CM-CMD) message to theAMS so as to instruct activation of the assigned secondary carrier(s)C_(—)1 and/or C_(—)2 (S906).

Fourth Exemplary Embodiment

The fourth exemplary embodiment illustrates that an ABS transmits atrigger condition to an AMS via a unicast message when the ABS wants toreceive SCN-REP message from the AMS in case where another triggercondition other than a predefined trigger condition has been satisfied.

At present, IEEE 802.16 defines the following three methods fortransmitting to an ABS scan results of inactive carriers for secondarycarrier activation or scan results of a neighbor ABS for HO.

(1) 0b00: No report

(2) 0b01: Periodic report

(3) 0b10: Event-triggered report

(4) 0b11: One-time scan report

That is, the ABS may inform the AMS of which one of the three methods isused to transmit SCN-REP, by a report mode of SCN-RSP message.

Also, IEEE 802.16 currently describes that an ABS transmits the triggercondition for each neighbor ABS or secondary/neighbor carrier to an AMSthrough broadcasting, as one example, via AAI_SCD, AAI_MC-ADV orAAI_NBR-ADV message. That is, the ABS may not transmit the triggercondition for a target to be scanned to the AMS through unicasting.

The following Table 20 shows an example of including trigger conditionswhen a report mode of SCN-RSP message is set to ‘0b10’ (Event-triggeredreport).

TABLE 20 Field Size Description Condition Recommended_Carrier_Index 6Recommended physical carrier index for scan at each neighbor ABS. Asdefined in AAI_Global-CFG message . . . Neighbor ABS index 8 ABS indexcorresponds to the position of ABS to be scanned in AAI_NBR-ADV messageNeighbor-specific variable Neighbor-specific triggers Present whenTrigger with encoding defined in Report mode-0b10 Table 9-12 Trigger andthe description corresponding carrier is required to apply differenttrigger condition from definitions of AAI_SCD message. . . . RecommendedCarrier 6 Recommended physical Index carrier index for scan at eachneighbor ABS. As defined in AAI-Global-CFG message Neighbor-specificVariable Neighbor-specific triggers Present when trigger with encodingdefined in Report mode = 0b10 Table 9-12 Trigger and the descriptioncorresponding carrier is required to apply different trigger conditionfrom definitions of AAI_SCD message. . . .

Referring to Table 20, when the report mode is the event-trigger report(as one example, ‘0b10’) and scanning for OH is requested, the triggercondition for transmitting the scan results of each neighbor ABS or acarrier(s) of neighbor ABSs may be informed to the AMS via SCN-RSPmessage.

Therefore, upon reception of the AAI_SCN-RSP message including the abovetrigger condition, the AMS may perform scanning for the correspondingABS or carrier(s), and transmit a scan reporting message to the ABS whenthe corresponding trigger condition is met.

The following Table 21 shows another example of including triggerconditions when the report mode of SCN-RSP message is set to ‘0b10’(Event-triggered report).

TABLE 21 Field Size Description Condition . . .Recommended_Carrier_Index 6 Recommended physical carrier Present if AMSat S-ABS index of the S-ABS the AMS decides to scan other plans to scan.carriers of the S-ABS. PCC-specific Trigger Primary Carrier Present whendefinitions Change-specific triggers with Report mode = 0b10 encodingdefined in Table 9-12 and the Trigger description corresponding carrieris required to apply different trigger condition from definitions ofAAI-SCD message. CA Trigger definitions Carrier Activation-specificPresent when triggers with encoding defined Report mode-0b10 in Table9-12 CA-specific and the Trigger description. corresponding carrier isrequired to be scanned for carrier activation.

Referring to Table 21, when the report mode is the event-triggeredreport (as one example, ‘0b10’) and scanning is requested from the AMSfor secondary carrier activation, a carrier activation-specific(CA-specific) trigger definitions for transmitting the scan results ofeach secondary carrier to the ABS may be informed via SCN-RSP message.

Also, when the report mode is the event-triggered report and thescanning is requested for primary carrier change, PCC-specific triggerdefinitions for transmitting scan results of each target inactivecarrier may be informed via SCN-RSP message.

Consequently, upon reception of AAI_SCN-RSP message including thetrigger condition from the ABS, the AMS may perform scanning for thecorresponding carrier and then transmit a scan reporting message to theABS when the corresponding trigger condition is met.

FIG. 10 is a block diagram of a wireless communication system inaccordance with one exemplary embodiment.

An ABS 1010 may include a controller 1011, a memory 1012 and a radiofrequency (RF) unit 1013.

The controller 1011 may be configured to implement proposed functions,processes and/or methods. Radio interface protocol layers may beimplemented by the controller 1011.

The controller 1011 may control a message (as one example, MC-ADV),which includes scan reporting trigger conditions for inactive secondarycarriers, to the AMS when decided to activate inactive secondarycarriers.

The memory 1012 may store protocols or parameters for scan reportingtrigger conditions of inactive secondary carriers. The RF unit 1013 maybe connected to the controller 1011 to transmit and/or receive radiosignals.

An AMS 1020 may include a controller 1021, a memory 1022 and an RF unit1023.

The controller 1021 may be configured to implement proposed functions,processes and/or methods. Radio interface protocol layers may beimplemented by the controller 1021. The controller 1021 may control thescan results to be transmitted to the ABS via a scan reporting messagewhen a scan reporting trigger condition of inactive secondary carriersis met according to the scan results of the inactive secondary carriers.

The memory 1022 may be connected to the controller 1021 to storeprotocols or parameters for scan reporting of the inactive secondarycarriers. The RF unit 1023 may be connected to the controller 1021 totransmit and/or receive radio signals.

The controller 1011, 1021 may include application-specific integratedcircuit (ASIC), other chipset, a logical circuit and/or data processor.The memory 1012, 1022 may include a read-only memory (ROM), a randomaccess memory (RAM), a flash memory, a memory card, a storage mediumand/or other storage device. The RF unit 1013, 1023 may include abaseband circuit for processing radio signals. In a softwareimplementation of the embodiment, the aforesaid schemes may beimplemented by a module (process, function, etc.) for performing theaforesaid functions. The module may be stored in the memory 1012, 1022,and performed by the controller 1011, 1021. The memory 1012, 1022 may bepresent inside or outside the controller 1011, 1021, or connected to thecontroller 1011, 1021 via various well-know elements.

What is claimed is:
 1. A method for transmitting a measurement reportmessage by a user equipment in a wireless communication system, themethod comprising: configuring a first type carrier and at least onesecond type carrier; receiving measurement report configurationinformation related to the at least one second type carrier via thefirst type carrier, the measurement report configuration informationincluding an indicator indicating an event-triggered measurement reportand information related to a measurement report triggering condition forthe at least one second type carrier; performing a measurement for theat least one second type carrier; determining whether the measurementreport triggering condition is met; and transmitting a measurementreport message including a measurement result for the at least onesecond type carrier via the first type carrier when the measurementreport triggering condition is met.
 2. The method of claim 1, furthercomprising: performing a measurement for at least one neighbor cell,wherein the measurement report message further includes a measurementresult for the at least one neighbor cell.
 3. The method of claim 1,wherein: the first type carrier is used to transmit downlink (DL)control information and uplink (UL) control information; and the atleast one second type carrier is not used to transmit uplink (UL)control information.
 4. The method of claim 1, wherein: the first typecarrier corresponds to a primary carrier; and the at least one secondtype carrier corresponds to a secondary carrier.
 5. The method of claim1, wherein the at least one second type carrier is initiallydeactivated.
 6. The method of claim 5, wherein the at least one secondtype carrier is activated according to a medium access control (MAC)message indicating activation of the at least one second type carrier.7. The method of claim 1, wherein the first type carrier is alwaysactivated.
 8. A user equipment (UE) for transmitting a measurementreport message in a wireless communication system, the UE comprising: areceiver configured to receive information; a transmitter configured totransmit information; and a processor configured to: configure a firsttype carrier and at least one second type carrier; control the receiverto receive measurement report configuration information related to theat least one second type carrier via the first type carrier, themeasurement report configuration information including an indicatorindicating an event-triggered measurement report and information relatedto a measurement report triggering condition for the at least one secondtype carrier; perform a measurement for the at least one second typecarrier; determine whether the measurement report triggering conditionis met; and control the transmitter to transmit a measurement reportmessage including a measurement result for the at least one second typecarrier via the first type carrier when the measurement reporttriggering condition is met.
 9. The UE of claim 8, wherein: theprocessor is further configured to perform a measurement for at leastone neighbor cell; and the measurement report message further includes ameasurement result for the at least one neighbor cell.
 10. The UE ofclaim 8, wherein: the first type carrier is used to transmit downlink(DL) control information and uplink (UL) control information; and the atleast one second type carrier is not used to transmit uplink (UL)control information.
 11. The UE of claim 8, wherein: the first typecarrier corresponds to a primary carrier; and the at least one secondtype carrier corresponds to a secondary carrier.
 12. The UE of claim 8,wherein the at least one second type carrier is initially deactivated.13. The UE of claim 12, wherein the processor is further configured toactivate the at least one second type carrier according to a mediumaccess control (MAC) message indicating activation of the at least onesecond type carrier.
 14. The UE of claim 8, wherein the first typecarrier is always activated.